Collection of mods for Beresford TC-7520

[lemon]

Leo,
there is no DC offset in my solution.
Btw, I would appreciate if you explain me, what is happening here? - Related posts 1425, 1430

[Codifus]

Leo,
there is no DC offset in my solution.
Btw, I would appreciate if you explain me, what is happening here? - Related posts 1425, 1430

Lemon, you may wan to try your tests with only one opamp installed on the line-out side of the 7520. I noticed that with only one opamp, the system is louder and a bit clearer too.

CD

[PaulJ]

I have modified my TS-7510 and the TS-7520 of a friend of mine. I have used a 1 uF auricap (MKP) and a Audio Note copper foil capacitor (I think it’s like paper in oil, but then more expensive).
These should be one of the best coupling capacitors you can get, but the direct connection (without capacitor) at the output of the DAC is a lot better.

Before this experience, I never thought that you could hear a capacitor. It worries me a bit because there are still some other capacitors in the signal chain (loudspeaker filter).

It is important that you disconnect the opamp circuit in order to reduce the load of the DAC. The input resistance of the opamp circuit is about 4k7 (TS-7510) and that is already the limit of the DAC. I think the load of the DAC should be as low as possible (is high resistance) to minimize distortion.

My amplifier does not have a coupling capacitor. It has a potentiometer directly coupled to the gate of a Tube amplifier (only the first stage is a tube). So, the DC level at the DAC output ( 2.5V) is connected to the gate of the tube. The potentiometer is 100k and has no problem with the DC voltage. The only problem is that the gate cathode voltage is decreased by the input voltage. The same happens with a normal AC coupled input signal so I don’t think it will do any harm. This DC level is (in my case) dependent of the volume level of the potentiometer. So only when you play at maximum level, you have the full 2.5V at the input.

@lemon
Do you mean the phase shift between the two outputs? Normally there should be no phase shift at relative low frequencies. A filter causes a phase shift.

[lemon]

....@lemon
Do you mean the phase shift between the two outputs? Normally there should be no phase shift at relative low frequencies. A filter causes a phase shift.

Yes, exactly! There is a phase shift, which starts from 5KHz (little) and rises as the frequency increases (attached is 20).

I you compare the sinus btw 5KHz and 20KHz, it appears that the phase shift is for the fixed output (opamps)

[Covenant]

Leo, when you have a spare few minutes could you please transfer the latest (appropriate) Caimen mods over to this thread?

[leo]

Leo, when you have a spare few minutes could you please transfer the latest (appropriate) Caimen mods over to this thread?

Which mods you mean mate? theres the cap changes posted by Stan (those grey ones on the audioboard) please remind me what else there is and I'll add em

[Covenant]

From here: http://theartofsound.net/forum/showt...?t=4580&page=5
onwards but you need to separate power regulation stuff which is only suitable for the Caiman (I think).
Sorry to give you some work Leo.

[StanleyB]

but you need to separate power regulation stuff which is only suitable for the Caiman (I think).

I have been playing about with the regulator upgrade from the Caiman on the TC-7520. The main issue is that the Murata regulators require some effort in order to get hold of them. Other than that, it works fantastic with the Caiman PSU.
We need help from someone who can order a batch of the Murata regulators, or we nee dto band together and do a group buy via Mouser in order to reduce their handling and shipping cost.

[Covenant]

Hmm interesting-so 7520 owners can take advantage of the Caiman power supply if the Murata's are fitted? I wonder if this might appeal to Tirna as they must know the 7520 well by now-I can think of a few people, including me, who would be happy to get them to do this work

[leo]

From here: http://theartofsound.net/forum/showt...?t=4580&page=5
onwards but you need to separate power regulation stuff which is only suitable for the Caiman (I think).
Sorry to give you some work Leo.

I've not tried the Murata regs yet, a few type regs I tried in the Caiman/7520 was discrete including some designed by John Swenson (schematics floating about on the net somewhere) , main reason I didn't post anything was because their not something you can buy off the shelf, I had to build them on matrix boards, their fiddly and a little time consuming doing them like this, a small laid out pcb would be much easier and quicker. building these things yourself is ok but its so easy to make a mistake and end up killing the dac chip or input receiver so I tend to be cautious recommending such mods to a commercial dac, soon as I get hold of some Murata's I'll compare them against the discretes and post results, pics etc. if they prove to perform the same or better than the discrete jobs it makes sense to go with the Murata's tbh rather than waste time and effort building your own

With the diy dacs I usually go mad with the mods etc but with the Caiman I try to keep things a little more simple so it would be easier for more folks to try